Nasality meter



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W. C. DERSCH v NASALITY METER oct. 2s, 1966 2 Sheets-Sheet 1 Filed May9. 1963 Tira@ ATTORNE Y oct. 25, 1966 Filed May 9. 1963 AMPMETER MiCROFIG.4

w. C. DERSCH NAsALI'rY METER me PERsoNs,ALL

2 Sheets-#Sheet 2 W/LL-/AM C. DERSCH FLEHR @f SWA/N ATMP/vers UnitedStates-Patenti@ i' 3,281,534 NASALITY METER Williamr C. Dei-sch', 110Cardinal Lane,Los Gatos, Calif. Filed -May 9,' 1963, Ser. No. 279,154

16 Claims. (Cl. 179-1) This invenion pertains to speech measuringequipment and more particularly to a meter and methodvfor measuring thenasal quality ofspeech. This measure, inturn, can be significant inevaluating the treatment. of: cleft palate patients.

Briefly, by way of background, it should be understood that air expelledduring speaking escapes through both the nose and mouth. When formingcertain sounds, thevvelopharyngeal valve (i.e., a smallflap locatedtothe rear of the throat) serves to block the air passage linto thenose. Formation of certain other sounds moves the flap to open thepassage permitting air to pass into the nose. Thus, in pronouncing aword such as 011, little air enters the nasal resonant chamber whilenine admits considerable air to provide a distinct nasal quality. l

Where a person is formed with a cleft palate, they velopharyngeal valveis either missing entirely (as is usual) or badly deformed andinoperative. Thus, the cleftpalate patient experiences seriousdifficulty in controlling the nasal quality of his speech.

In an effort to impart a certain amount of control over the nasality ofthe patients speech, aprostheticdevice or obturator is supported at theroof oftheumouth and disposed to serve as something of a substitute forthel missing flap. Fitting a patient. with such ahdevice isf performedon a cut and try basis. The degree of successl is measured by listeningto the patient speak or by emplying oral manometry or cineradiography(X-ray motion pictures), or a combination of these techniques.

One method of treatment of cleft palate patients follows a programemploying graduated obturators. Other methods employ surgery. Evaluationof speech` competence by merely making a subjectivev assessment has beensufficiently crude to preclude the reaching of reliable conclusionsregarding the merits of the various treatments. Devices to provideobjective measurement of cleft palate performance, have included oralmanometers,` the sound spectrograph, and cineradiographic equipment.Each of these measuring tools has been subject to significantlimitations. What has been needed, in short, is a simple and reliablemethod or means for accurately measuring speech competence andparticularly the nasal quality of speech.

In general, it is an object of the invention toV provide a meter foraccurately measuring the nasal `quality of r speech.

Equipment for the above purpose must, of course, sort out spoken soundsfrom background noises and the like. A relatively recent but extremelypowerful technique which detects the occurrence of certaincharacteristics and particularly voiced sounds is employed herein.Voiced sounds are defined in this art as those sounds which originatewith air passing through the Ivocal chords and which are modulated byphysical changes inthe various resonant chambers in the throat and mouthof the speaker. These sounds are distinguished from unvoiced soundswhich areformed primarily by air passing through constrictive chambersin the throat, mouth or at the teeth or lips. Voiced sounds are likecomplex multifrequency waves, but are not truly periodic and have dampedoscillatory characteristics` The voiced sounds do, however, have forfundamental as well as harmonic frequency components relatively briefbut discernible intervals, and these components can usually beidentifiedy The unvoiced sounds contain little or no such fundamentalfrequencies, which are usually of the order of a lfew hun- Patented Oct.25, '1966 2 dred to a fewv thousand cycles per second, but are noise?like in characteriand consist of essentially randomampliftudevvibrations with time.

By way of providing furthervbackground, in the present invention;meanstarevprovidedy which sensitively disti-n'- guishY voiced frombothrunvoiced soundsand ambient noise by detectingthe occurrence of anasymmetry characteristic inelectrical signal representations of humanspeech. The

'asymmetry'characteristic is present only in voiced sounds, but ispresentineach case therein, and results in an arn- A plitude-edifferencebetween positive-going peaks and negative-going'rpeaksin the complexmultifrequency voiced sound wave. The complexwave issplit intopositive-going andcnegative-going cyclic components and the differencebetween them providesthe asymmetry characteristic.

t In a specific example as used herein, electrical signalrepresentations. of human speech either prerecorded or from `amicrophone input are given a phase shift to favor nasal soundfrequencies and then applied-to a pair .of parallel-'coupledoppositely-poled diodes. One of the diodes passes thepositive-goingsignal components in lthe complex multifrequencywave andthe other diode v passes the negative-going signal components.

Each vof these com-ponentwaves isthen applied to a peak charging circuitAwhich has a time constant corresponding to a typical syllabic speechinterval.

I havediscovered vth-at the ratio oftheintegrated values of.eachcomponent provides a nasality quoticnt which reliably characterizesthe nasal quality vof a persons speech. Another object ofthe inventiontherefore is to provide a method andk means for deriving a nasalityquotient which is characteristic of an individuals speech competenoe.

Accordingly, to derive the nasality quotient of an individual, I formelectricall representations of speech as a .phase shifted complex wavehaving two'concunrently existing cyclic components. The two componentsare each time averaged over. a predetermined interval to provide a pairof signals respectively representing afirst and second nasality factor.Then for the period of a selected aspoken message or speech event (asdefined below) I integratek each signal to derive a value for eachfactor and store the values derived. I then sense the value of eachfactorto establish the ratio therebetween. This ratio can subsequentlybe plotted on a graph for comparison with an established norm orotherwise utilized `as desired.

Other objects of the invention will become more readily apparent fromthe following detailed descriptionof a prefer-red embodiment when takenin conjunction with the drawings in'which:h

FIGURE 1 .is a block diagram representation of a nasality meteraccording to the invention.

FIGURE 2 is a schematic electrical circuit diagram according to theinvention.

,FIGURE 3 shows a typical graph wherein the nasality quotient for eachof ten individuals has been plotted.

, FIGURE 4 is a schematic electrical circuit diagram similar to FIGURE 2with ythe application of associated `values to the various componentstherein.

FIGURE 5 is another` embodiment according to the .sound discrimina-tingcircuit for converting electrical speech representations into a phaseshifted complex wave 0 having two concurrently existing cycliccomponents.

Means are provided for time averaging each of the components over apredetcrmined'interval to provide a pair of signals respectivelyrepresenting a first and second nasality factor. Means for integratingand storing each signal over the period of a selected spoken message orspeech event is further provided in a manner to derive and store a valuefor each of the two nasality factors. Further, means are provided forsensing the values to provide a nasality quotient for the speechrepresentations, as defined by the tratio between the two values.

Referring to FIGURE 1, a preferred embodiment includes means forproviding electrical representations of human speech. Thus, the speechto be measured can be examined from either a microphone input 11 or viaa playback transducer 12 arranged to play back :previously recordedspeech events. A speech event for present purposes can be defined as aword, words, phrase or other speech-generated sound for measurement. Therecitation of digits 0-9 can be a speech event, as can the pronunciationof San Francisco.

The electrical representations are fed to a nasality wave structurediscrimination circuit 14 adjusted to favor nasal sounds asdistinguished from other sounds. lt has been observed that changes inphase relation cause the output signal of circuit 14 to vary uniquelyand identifiably with time for particular types of voiced sounds. Thus,for different phase shifts the characteristic asymmetry pattern arisingduring a syllable speech interval may vary, and with certain adjustmentscan favor positive-going cyclic components or negative-going cycliccompounds.

In the circuit of FIGURE 2 electrical input signals representative ofhuman speech are amplified as provi-ded from a source such as microphone11 or transducer 12. These representations are applied through a DCblocking capacitor 20 to a phase shifter 22. Here the phase shifter 22includes a transistor 24, shown as being of PNP conductivity type, byway of example. Transistor 24 has its base 25 coupled to a minus biasthrough a resistor 30, and its collector 26 coupled to a -12 volt supplysuch as battery 32 via a resistor 33. A manually controlled main powerswitch 35 is disposed in the co1- lector circuit and is preferablyaccessible on the outside of a housing (not shown) enclosing the meterelements. The emitter 27 of transistor 24 is coupled to ground through aresistor 36.

A selected phase delay may be introduced into the monofrequencycomponents of the amplified signals from transistor 24 by a passivecircuit arranged to couple collector 26 and emitter 27. The passivecircuit includes a capacitor 38 coupling collector 26 to a circuitjunction point 40. An adjustable resistor 42 couples emitter 27 to thesame point 40. This phase shifter 22 passes all frequencies of interestbut the amount of phase shift introduced for any monofrequency componentis dependent both upon the setting of the adjustable resistor 42 and thefrequency itself.

As will be further explained below, varying the setting of resistor 42serves to establish a norm or standard representative of the nasalquality of normal speaking people in a given region or locality. Thus,the nasality of persons with an impaired speech competence can bemeasured against a regional or localized standard of nasality.

The phase-shifted complex wave appearing at circuit junction 40 isapplied through a Vpower amplifier 44 to means for forming the complexwave into two concurrently existing cyclic components.

Thus, a wave splitting circuit includes a pai-r of parallel oppositelypoled semiconductor diodes 46, 47 which perform the wave splittingfunction. A first ofthe diodes 46 is poled to pass the positive-goingcyclic components, while the second diode 47 is poled to passnegative-going cyclic components. With the reference axis of the wavesbeing substantially at ground potential, this circuit provides accuratebut separate representations of the positive and negative cycliccomponents of the coniplex multifrequency wave. t

Means for time averaging cach of the components over a predeterminedinterval to provide a pair of signals respectively, representing a firstand second nasality factor is shown in FIGURE 1 as the time averagingcircuit t6, 17. Thus, the nasality rfactors can be considered us therate integrated wave components.

Circuits .16, 17 can be in the form of peak charging circuits. Forexample, a peak charging circuit is coupled to diode 46 and consists ofa shunt capacitor 50 coupled to ground and a parallel resistor 51likewise grounded via a circuit junction point 53. The peak chargingcircuit coupled to diode 47 also consists of a shunt capacitor 55 and aparallel resistor 56 both coupled to ground. Thus, resistors 51, 56 forma grounded, center tap voltage divider whereby signals appearing acrossresistor 51 represent a first nasality factor and signals appearingacross resistor 56 represent a second nasality factor.

Diodes 46, 47 have matched characteristics as do the two peak chargingcircuits so that like amplitude variations result for signals developed-across resistors 51, 56 for like absolute amplitude variations derivedfrom thc phase shifter 22. r

The discharge time constants of the peak charging circuits are alike andselected to be on the order of ms. corresponding to a typical syllabicspeech interval. Signal variations occurring across resistors 51, 56appear as relatively slow varying output signals. Signal variations forthe positive-going Iand negative-going componcnts occurring acrossresistors 51, 56 respectively appear as relatively slow varying outputsignals which can each be integrated over the period of a speech eventand stored. Thus with this arrangement the phase delay can be set byresistor 42 to favor nasal wave structure and thereby provide anasymmetry characteristic representative of nasality whereby thepositive-going cyclic component, time averaged over the syllabicinterval, will provide a nasality factor which can be integrated andstored. Similarly the negative-going cyclic component will also be timeaveraged to provide a second nasality factor to be integrated andstored. Means for integrating and storing each signal (representing oneof the factors) for -the period of a selected speech event whereby thevalue of each factor for the period can be derived and stored isrepresented by boxes 18, 19. Thus, in FIGURE 2 a pair of summingintegrator circuits are provided to integrate and store the signalcomponents appearing across resistors 51, 56 respectively. To integrateand store the positive components, a diode 61 poled to pass positivewaves and a series-coupled resistor 62 and relatively large capacitor 63are disposed in shunt with resistance element 51. Similarly forintegrating and storing native cornponents representing a secondnasality factor there is provided an oppositely poled diode 64series-coupled with resistance element 65 and capacitor 66. Similarly,diode 64, resistor 65 and capacitor 66 are disposed in shunt acrossresistance element 56.

During the period of time when the signal appearing at the junctionbetween resistor 51 and diode 61 is above ground a charge is built up inthe relatively large capacity condenser 63. As the signal becomesnegative with respect to ground, diode 61 serves to block the drainingaway of the charge and accordingly for each subsequent positive-goingcomponent the charging condenser 63 is further built-up. Similarly fornegativegoing components an opposite charge is built up in condenser 66.

Means for sensing the stored charge in each of storage elements 63, 66is provided whereby the value stored in each can be selectively rend.Thus, a pair of normally open circuit branches 67, 70 are respectivelycoupled to the junction points between condenser 63 and resistanceelement 62 and between condenser 66 and -resistor 65. A meter, such asan ammeterf'68, disposed in shunt with a damping resistor 69 andconnected to ground is series-connected through a scale factorresistance 71 to a manually operated switching means 74 selectivelyoperable to connect meter '68 to terminal 72 or 73 to read thestored'charge in storage element 63 or 66 respectively.

Means are provided for resetting storage elements *'63, 66 to arelatively uncharged condition simultaneously. The storage reset meansis manually operative, as by a push button. As shown in FIGURE 2 thereset means includes a pair of contact points`75, 76 connectedrespectively to branches 67, 70. A conductive and grounded l armature 77is spring 'urged away `from contact `points 75, 76 by a spring 78whereby push button 79 Acan ybe employed to simultaneously ground thevpoints 75, 76 by contacting same. Thus, in the event that a reading outof the values stored inelements 63,66 fails to drain -them of theirrespective charges, prior to each subsequent speech measurement, pushbutton 79 can be utilized to virtually instantaneously withdraw thestored factors to reset the storage elements 63, 66 to a predeterminedvalue, namely, to ground.

While the `above system has been described in sufficient detail toenable one skilled in the art to` practice the invention, aspecificfexample of the complete ci-rcuit together with values, voltagesand other pert-inent identifying information is disclosed in FIGURE 4.Unless noted bythe symbol omega (Q) all resistance values are inkilo-ohms. When indicated by the omega symbol the resistance values aremeasured in ohms. The lcapacitors are all measured'in microfarads.

Power amplifier 44 can be of conventional construction providing a gainon the order of twenty decibels and adjustable to compensate for themicrophone selected. Meter 68 can be of conventional construction suchas an ammeter having a range between plus and minus 50 microamperes.

In operation, assuming the switch 35 is closed, a person can be asked torecite into microphone 11 the digits oh to nine thereby acumulating thestoring of the respective values of a first and second nasality factorin condensors 63, 66. These values are then selectively read by movingswitch 74 to terminal 73 and then to terminal 72. Dividing thefirst-read value by the second-read value provides a nasality quotient.For example, as shown in FIGURE 3, D. J. has a nasality quotient ofapproximately 1.3. The nasality quotient for five normal persons isshown plotted against unity as a base reference. Of the ve normalpersons, note that F. S. had a head cold thereby generating a nasalityquotient showing more nasality than the others. Five persons having acleft palate problem, thereby being precluded from closing the airpassage to the nose, showed more nasality with the exception of S whowas fitted with a prosthetic device, or obturator, for correcting thecleft pala-te speech deficiency. Thus, a program of progressiveobturators can be evaluated by periodically making truly objectivemeas-` urements of the nasality of the persons speech.

According to another embodiment of the invention as shown in FIGURE 5,nasality in speech can be continuously monitored by direct couplingmeter 68 to branches representations into a phase-shifted complex wavehaving two vconcurrently existing cyclic components, means for timeaveraging each of thecompo'nents over a predetermined interval ltoprovide agpair of signals respectively representing a first `and vsecondnasality factor, means `for'integratingand'storing each said signalduring speech over the period of a selected speech event to A'derive a"stored value foreach said factor, and 'means for sensing said storedvalues toprovide a nasality`qu'ot`ient, for the representations, definedbythe ratio `betiveen said values.

3. A meter as defined in claim 2 wherein the lastrnamed means includesswitching means lfor selectively sensing said values.

4. A meter for measuring 'the nasal quality kof 'electricalrepresentations of speech comprising a voiced sound 'discriminatingcircuit for converting electrical speech representations vinto a phaselshifted complex wave `having two concurrently existing cycliccomponents of opposite polarity sense, means for time averaging each ofthe j components lover 'a predetermined interval to provide a 67, at ajunction point 81. Thus, while a person speaks continuously'intomicrophone 11, phase shift control (resistor 42) is varied to null themeter 68 at its midpoint. The degree of displacement of the wiper forresistor 42, properly calibrated, then provides a direct readingrepresenting the -individuals nasality quotient.

I claim: f

1. A method of measuring the nasal quality of speech comprising thesteps of forming electrical representations of voiced sounds as a phaseshifted complex wave having two concurrently existing cycliccomponents', time averaging each of the components over a predeterminedinterval to provide a pair of signals respectively reprepair of signalsof opposite polarity respectively representing a first and secondnasality factor, means serving to integrate and store each said signalover the period of a selected speech eventto derive a stored value fore-ach said factor, and means for sensing said values to provide anasality quotient, for the representations, as'defined bythe ratiobetween said values. l

5. A meter as defined in claim 4,*further including switching means forselectively sensing each of said values.

, '6. A meter as defined in claim 4, furtherincl'uding means forresetting said storage means to remove said stored values.

7. The method of measuring the nasal quality of speech comprising thesteps of forming electrical representations of speech as a complex wave,shifting the phase of said complex wave, splitting saidphase-shiftedcomplex wave into two concurrently existing cyclic components, timeaveraging each of the components over a predetermined interval toprovide a pair of signals respectively representing a first and secondnasality factor, integrating and storing each said signal over theperiod of a selected speech event to derive a stored value for eachsaidfactor, sensing the value of each factor to provide a ratiotherebetween defining a nasality quotient, and withdrawing the storedfactors from storage to reset same prior to receiving a factor for asubsequent speech event.

8. A nasality meter for measuring' and indicating the nasal quality ofspeech comprising means serving to provide a complex multifrequencysignal representative of speech, means serving to shift the phase ofsaid complex signal to emphasize a predetermined nasal Wave structure,means responsive to the phase shifted complex signal serving to dividethe signal into two concurrently existing cyclic components, means fortime averaging each of the components over a predetermined interval toconstitute said components a first and second nasality factor, meansserving tonintegrate each said factoral component during a selectedspeech event to derive the value thereof and to separately store saidvalues, and means for indica-ting the storedvalue of said each componentto provide a nasality quotient defined by the ratio between said values.

9. A nasality meter as defined in claim 8 wherein the last-named meansfurther includes means selectively operable to visually indicate thestored value of each said component independently.

10. A nasality meter as defined in claim 8 wherein the penultimate namedmeans includes means for selectively resetting same to a predeterminedvalue.

1l. A nasality meter as defined in claim 8 wherein th last-named meansincludes electrical measuring means and manually operable switchingmeans serving to selectively couple said measuring means to read outeither of said stored values independently whereby the ratio of saidvalues can provide a nasality quotient for said speech event.

12. A nasality meter as defined in claim 11 further including manuallyoperable means for resetting said storage means to a predeterminedvalue.

13. A meter for measuring the nasal quality of electricalrepresentations of speech comprising means for shifting the phase ofcomplex speech waves among said electrical representations to provide aunique asymmetry characteristic thereof, means for splitting thephase-shifted complex wave into two concurrently existing cycliccomponents, means for time averaging each of the components over apredetermined syllabic interval to provide a pair of signalsrespectively representing a first and second nasality factor,integrating and storage means including a pair of oppositely poledunilateral conducting elements each series-coupled to an associatedresistancecapacitive summing circuit, said unilateral elements beingrespectively coupled to pass only one or the other of said components toseparately derive and store the respective values of the components forthe period of said speech event, and means serving to selectively readout and visually indicate each of said stored values, the lastnamedmeans including a meter having a visual scale and manually operableswitching means for selectivelyreading out the stored value of either ofsaid summing circuits.

14. A meter as defined in claim 13 further including means for resettingsaid summing circuits including manually operable means forsimultaneously equalizing the charge on said respective capacitiveelements.

15. A meter for measuring the nasal quality of electricalrepresentations of speech comprising a voiced sound discriminatingcircuit for converting electrical speech representations into aphase-shifted complex wave having two concurrently existing cycliccomponents, means for time averaging each of the components over apredetermined interval to provide a pair of signals respectivelyrepresenting a first and second nasality factor, means for integratingeach said signal during speech yto derive a value for each said factor,and means for sensing said values to provide a nasality quotient, forthe representations, dened by the ratio between said values.

16. A meter for continuously monitoring the nasal quality of speechrepresentations comprised as defined in claim 15 and further includingmeans for varying the degree of phase shift applied to said complex waveand connected to vary one of said components with respect to the otherto equalize same, whereby the degree of variation required to equalizesaid components provides a measure of the nasality quotient of thespeech.

No references cited.

KATHLEEN H. CLAFFY, Primary Examiner.

R. MURRAY, Assistant Examiner.

1. A METHOD OF MEASURING THE NASAL QUALITY OF SPEECH COMPRISING THESTEPS OF FORMING ELECTRICAL REPRESENTATIONS OF VOICED SOUNDS AS A PHASESHIFTED COMPLEX WAVE HAVING TWO CONCURRENTLY EXISTING CYCLIC COMPONENTS,TIME AVERAGING EACH OF THE COMPONENTS OVER A PREDETERMINED INTERVAL TOPROVIDE A PAIR OF SIGNALS RESPECTIVELY REPRESENTING A FIRST AND SECONDNASALITY FACTOR, INTEGRATING EACH SAID SIGNAL OVER THE PERIOD OF ASELECTED SPEECH EVENT